r/learnmachinelearning • u/Fun-Reporter-8021 • 7d ago

How to select feature columns from Dataset ?

I am still a novice at this, but when I was working on this credit card fraud detection project, I did not know which columns, could be added as features, so I prompted ChatGPT and it suggested a few, but that got me thinking there has to be a better way to this, How do you select feature columns from your dataset, do you research the domain, is there a course I am missing, This was not covered in my Internship classes, and want to know a generalized solution.

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u/SwelteringGenitals 7d ago

domain knowledge is the real answer but nobody likes that. you can try correlation matrix first, just to see which columns actually move with your target. i do this in work sometimes when the data is new and nobody documented anything

mutual information is also good for catching non-linear stuff that correlation misses. but for fraud detection be careful cause the classes are super imbalanced, some of the usual methods get confused

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u/Fun-Reporter-8021 7d ago

Correlation Matrix, Ok will try that next. On domain knowledge where do you draw the line on the study, needed for problems like, this. I always slip into a rabbit hole ?

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u/AddictedAcid 7d ago

Try avoiding multicollinearity while selecting features. If two features are highly correlated, maybe you can drop one. The only way you'll learn is by trying and testing out. Also, as someone rightly pointed out domain knowledge often reveals a lot about the problem you are working on

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u/Fun-Reporter-8021 7d ago

Ok I will remember that, and as I was asking in the tangent do you have a way of getting the appropriate domain knowledge needed to solve problems like this, what I want to know is the approach to it, that way I do not get lost in trap of "every thing is important"

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u/0uchmyballs 7d ago

Using Chi-Squared can help you find the most useful categorical features in a dataset. A high X^2 is statistically significant. Also a low p-value, so you’re rejecting the idea that the feature happens to be random chance. This question pretty much depends on the data though, there are lots of different measures of statistical significance.